concat two array and avoid duplicates javascript code example

Example 1: javascript remove duplicate in two arrays

array1 = array1.filter(function(val) {
  return array2.indexOf(val) == -1;
});
// Or, with the availability of ES6:

array1 = array1.filter(val => !array2.includes(val));

Example 2: don't include duplicate value on concat js

let array1 = ['a','b','c']let array2 = ['c','c','d','e'];let array3 = array1.concat(array2);array3 = [...new Set([...array1,...array2])]